This invention relates to bearing assemblies and, more particularly, to bearing assemblies for supporting one end of a rotatable shaft against radial loads, such as the lower end of a drive shaft of an agitator extending into a mixing tank.
Chemical and food processing operations often employ mixing tanks including a vertical shaft which projects down into the tank and carries one or more impellers or agitator blades for mixing or agitating materials in the tank. The lower end of the drive shaft inside the tank typically is supported against radial loads by a bearing assembly mounted on the bottom of the tank.
When a corrosive and/or abrasive material is to be mixed, the bearing assembly usually is enclosed in the housing to isolate it from the material. Examples of such constructions are described in U.S. Peterson patent U.S. Pat. No. 3,443,794, U.S. Stratienko patent U.S. Pat. No. 3,489,469 and U.S. Davis patent U.S. Pat. No. 4,660,989.
In applications where the materials to be mixed are neither corrosive nor abrasive, the bearing assembly does not necessarily have to be isolated and a less complicated mounting arrangement can be used. For such applications, particularly food processing where certain sanitary conditions must be maintained, it is highly desirable for the bearing assembly to be designed to facilitate convenient cleaning while in place, that is, without any disassembly.
The bearing serves as a wear device and typically is made from a low friction synthetic plastic material which is inert to the material being mixed. The bearing tends to wear with use and must be replaced periodically. Some conventional bearing assemblies require considerable disassembly of the drive shaft to replace the bearing. Other conventional bearing assemblies permit a bearing to be replaced without disassembly of the agitator drive shaft; however, it is difficult to properly clean the bearing surfaces and other surfaces of the assembly exposed to the material being mixed while the bearing assembly is in place.